For the first iteration `mod->perm_map[sclassi]` is NULL, thus do not
use it as source of a memcpy(3), even with a size of 0. memcpy(3) might
be annotated with the function attribute nonnull and UBSan then
complains:
link.c:193:3: runtime error: null pointer passed as argument 2, which is declared to never be null
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
b98d3c4c53